Bernard Dell

Mediterranean type forest ecosystems commonly experience an extended dry period during summer months. In recent decades many Mediterranean regions have experienced elevations in temperature and decreases in rainfall, which have led to large-scale forest die-off events. This has also recently occurred in the Northern Jarrah Forest (NJF) (Matusick et al. 2012) and was closely associated with increased infestations by borers. These borers caused severe damage to jarrah and marri trees and contributed to increased tree stress and tree mortality.

Blue-stain (Ophiostomatoid) fungi, which attack woody tissue, can be closely associated with bark beetles. These fungi have been found in Eucalyptus species, invading the sapwood (van Wyk et al 2007), and appear to be present in the jarrah forest of Western Australia.

In this study, the occurrence and relationships between borers and blue-stain fungi in jarrah forest under drought conditions, is being investigated.

Background
• in situ deeply weathered granite profiles (Fig. 1) are common in South-Western Australia (SWA) (Fig 2).
• Roots of native trees penetrate up to 40m (Fig. 3) to access ground water.
• Deep soil carbon (>35 m) has recently been quantified in SWA (Fig. 4). This deep carbon accounts for up to five times more carbon than current world estimates (<30 cm).
• Deep rooted native vegetation in SWA has been replaced by shallow rooted annual crops (20.5 m ha) (Fig. 2iii).
• The composition, age and stability of this deep carbon is unknown. The impact of agricultural practices on deep carbon is also unknown. Here we report on the composition of deep soil carbon for one profile.